Stainless Steel Project Help(part 2)

Don,
Since we had gotten more and more off the original topic of "Mills and Drills" I didn't want to irritate anyone further and so started this thread to address what you told me.
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I originally wanted to go with 316L stainless steel when I was considering a larger lathe, but I'm now thinking more in terms of Aluminum and 303 stainless steel. But the following are details of the part of this project that *must* be made of 316L.S.S.
1.00" of a 2-1/2" long, 7/16" diameter rod must be turned down to 1/4" diameter. The 7/16" diameter end will be threaded so it can be screwed into a 316L stainless steel ball-knob. The 1/4" diameter end will fit into a 316L S.S. sleeve that will be 5/8" long, leaving a 3/8" area in the assembly that is 1/4" diameter. To keep this sleeve on the main rod I will need to drill a 1/8" hole all the way through the sleeve *and* the rod inside so I can slide a tight fitting 1/8" Delrin rod to lock them in place.
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Even though it's a "baby-step" I'm considering the Micro-Mark mini-mill to compliment the lathe.(Perhaps there will be compatible tooling between the two). I'm just wondering if the milling attachment for the lathe would make this unnecessary.(At least at this low level).
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Actually, this would be a "trench" with a square profile.(But it's one job I mentioned that I may not have to do).
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Then I definitely wouldn't try it on the Microlux lathe. :-)
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Yes. But just to reiterate, stainless steel is the extreme. And thanks to your advice I'm using it as a yardstick to determine what is and isn't plausible with the MM lathe.
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If I did end up doing this I would place a 1/16" Delrin "floor" inside the groove.(But as it stands now, I'm going with he Delrin "cup" idea so the bearings will touch only Delrin and not metal).
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MM sells a live center set for $92.65(#83185), and a live ball bearing center for $12.95(#82509). I'm also looking at that steady rest for $31.45(#82503) and the follower rest (#82504) on the Micro-Mark mini-lathe page, but it doesn't say "traveling".
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316L
After more reading here I've decided to drop the idea of getting the grinder attachment for the lathe. I want to make some of my own tools, so I'm studying up on bench grinders.
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I'm flexible on this at this point, but these rods will be about 1/2" in diameter, and I'll only need to mill 1/4" of the rod's end into a square.(A 1/4" thick disk with a square hole in the center will fit on the end of the rod).
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All I could find at Micro-Mark is the following: http://www.ares-server.com/Ares/Ares.asp?MerchantID=RET01229&Action Êtalog&Type=Product&IDƒ146
But there is somethng called an E-Z hand tapper on eBay.(I've also seen Enco tappers on eBay).
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I'll keep an eye on eBay.
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The diameter that I'll have to drill through is 7/16"(which would actually be the total of the rod inside the sleeve together).
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I'll add those to my shopping list.
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I'm going to have to search the internet for visual aids. Project sites are difficult to come by, and Yahoop Groups is a pain.(BTW. I do know that I'll also need some sort of indexing tool for making gears).
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And this may be done in Delrin instead if it comes to that.
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I don't have a schooling option, so I'll have to wing it. But you've given me a good idea of where to start.
Thanks a lot.
Darren Harris Staten Island, New York.

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    And -- I'm starting to burn out. You are adding an extra hour or more of typing to my evening newsreading time. (And, I'm going to be quite busy for the next two days, so I might not be able to answer much of anything during that time.
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    I still fail to see what gives the "must" for these.
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    O.K. As long as your lathe can handle 7/16" diameter though the spindle, this should work reasonably. Much beyond 1" length at 1/4" diameter would be a different matter.
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    Unless you can get the balls pre-threaded, this will call for rather high quality taps, and you will need to replace them fairly often, unless you are willing to use one until it breaks off in a workpiece, thus junking the workpiece before switching to a new tap.
    And -- you'll need a proper tapping fluid when tapping those balls. I don't know what is the best fluid for that, so I'll let others suggest for that. I don't work 316 SS.
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    Why not something like Locktite to fixture it in place without needing the drill and pin.
    And why Delrin? If people are getting frantic and applying a lot of force to this (it is sounding like the knob to a joystick), they may well shear the Delrin at only 1/8" diameter. I would suggest a roll pin instead, if you have room to drive it through when you need to remove it.
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    Some -- mostly between the milling attachment for the lathe and the real (but small) milling machine.
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    That depends on the size of your workpieces, among other things.
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    O.K. Easier to do on the milling machine with a rotary table to rotate the workpiece around the center of the circle formed by the trough.
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    If it is a square bottomed trough, you could turn it, using a tool ground as a trepaning tool (and with the workpiece held in a 4-jaw chuck, if it is small enough to be rotated around the center of the trough circle above the bed without hitting the bed.
    You cut a fairly narrow groove, them move out and plunge again until you get the full width. Then you move the tool sideways to smooth out the bottom of the groove.
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    No -- SS is *an* extreme. There are other things which are more difficult to machine -- though you have not yet mentioned wanting to machine them. These include hardened tool steel. (Better done with a toolpost grinder than a turning tool.)
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    O.K. How much force per ball? How long will it set in one place with the full load? That might cause the balls to indent the Delrin, making bumps as it moves later.
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    The set probably includes several special points for handling strange shaped workpieces, and you probably don't need that at present. Wait until you get a project needing that before ordering.
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    "Traveling rest" is a UK way of saying "follower rest" -- different terms, same item.
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    Which I have not used.
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    Far better. A grinder on the lathe leaves abrasive compounds on the ways, and leads to rapid bed wear. You have to jump through hoops to protect the bed and other parts of the lathe.
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    O.K. That should be doable on the milling attachment. The main trick (solved by the collet block) is having a way to turn the workpiece precisely 90 degrees for the next cut.
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    O.K.
http://www.ares-server.com/Ares/Ares.asp?MerchantID=RET01229&Action Êtalog&Type=Product&IDƒ146
    Neither of these are what I was talking about. Those are for tapping holes properly vertical in plates of material. And it might be difficult to hold the workpiece properly vertical, even with the vise shown as an accessory.
    What I am talking about are tapping *wrenches*, which form a T-bar around the end of the tap, and are turned by hand. The knob on the top of that tool you've ponted to will be too small for driving a 1/4" tap into stainless steel.
    Micro-Mark is *not* the be-all and end-all of machining supplies. Call up MSC, and register with them. They will send you a 4000+ page catalog, which can show you more than you ever imagined in the way of tools. And -- you can take it with you to the john, to learn more about what is available, which you can't do with a web page, unless you use a laptop and a wireless net connection. :-)
    But be careful to not loose circulation in your legs with that big catalog on your lap.
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    The steady rests should be ordered *with* the lathe, as they are specific to the lathe's design. Many other things are more adaptable.
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    O.K. A small benchtop drill press (perhaps $50.00 or less from eBay to get a junky one, but one which you can carry upstairs in one hand. It may be sloppy, however.
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    The two-flute ones are the best for milling slots. In England, they are called "slot drills" for that reason.
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    And -- of course, this depends on how large the workpiece is, since it has to rotate above the bed of the lathe without hitting it.
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    Good Luck,         DoN.

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No problem. I'm just trying to address all the loose ends, so my goals are clear. No need to spend so much of your time typing. You've helped me out a lot already. Not just with your direct responses(which have been pretty fast), but also with your archived posts I've spent hours reading.
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A gamer's hands can get pretty sweaty in the heat of battle.(But I'll have to settle for 303, since no one makes 316* 1-3/8" diameter ball knobs).
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The site page for my lathe makes reference to a 5/8" dia. thru-hole, so that may be it.
Much beyond 1" length at 1/4"
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Well, the rod will still be 2-1/2"(to 2-3/4") long. only 1" of it will be turned down to 1/4" from 7/16".
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The ball-knobs from McMaster Carr are pre-threaded. I just have to decide on which of the following eight threads to get.(Though I suspect that it'll make no difference).
1) 1/4" - 20 2) 5/16" - 18 3) 5/16" - 24 4) 3/8" - 16 5) 3/8" - 24 6) 7/16" - 20 7) 1/2" - 13 8) 1/2" - 20
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Because I want the option of taking it apart in the future for part replacement. I was however thinking of using Locktite where the rod screws into the ball knob. That is the fit that needs to be permanent.
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There will be no room for protrusions, so the length of the 1/8" diameter Delrin rod will equal the diameter it is placed in(which is 7/16"). I figure that Delrin(or nylon) in the proper size would make for a tighter fit than a metal pin. And I can just punch it out when I need to.
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Of course the work envelope(whatever that will be) will be the big difference, but outside of that I'll need to determine how big a difference there would be in other ways between this lathe(with attachment) and a mini-mill.
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The largest workpieces will be A) 4-1/2" square(6" diagonal), 3/16" thick, and B) 4" square, 1/4" thick. I'm actually *considering* using 5052 Aluminum.(6061 would be my second choice). The reason is because I'm concerned about the possibility that the stiffness of S.S. steel may cause the assembly to lock, and aluminum's flex may prevent that. I'm probably worried about nothing, because this part is basically a flat Delrin surface that will be sliding(a half inch in any direction) between upper and lower bearings situated inside Delrin cups.
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Actually, what I meant was that S.S. is the most estreme material *I* will be working with. :-)
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That's the reason for the *replaceable* Delrin ring(floor) idea. :-) But the downward force will for the most part be insignificant, since the push of the "race face" will tend to be horizontal. It's still smart to assume the occasional downward push(though there is no point to doing that), but again, these are prototypes and I will be getting feedback so I can determine where the weak links are.
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My intentions exactly.
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Ok. "Collet block". I'm on it.
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Yes, I know. I was just trying to indicate that that was all M.M. had(since I already had M.M. open in a browser window as I was typing). But if the "T-bar" is what you turn, then I'm confused, because the E-Z tappers and Encos I see have that.
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:-) I tried getting a catalog from them a couple of months ago with no luck. Even though they advertsie the catalog, there are no options for getting it.(My Grizzly catalog just arrived though).
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Ok, I guess I have to get the two I mentioned on the M.M. lathe page.
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Obviously "small" and "accurate" don't go together on any of these machines.
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My wording probably wasn't clear enough. Basically, I'll need to turn a 4-1/2" square(1/16" thick) plate into a 3" disk that has four 1/2" wide arms that are rounded at the ends.
I'll still need to get a rotary table, so I'll be searching the internet for a visual on anything relating to a rotary table on a lathe that has a milling attachment.
Thanks a lot.
Darren Harris Staten Island, New York.

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    I'm glad that you're digging through the archives, too.
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    What is wrong with the black Bakelite knobs which are also available with cast-in brass inserts with female threads for screwing onto your shaft? They are a bit lighter than the stainless steel, and certainly a lot less expensive.
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    Oops! That means that you will need to learn to use the fixed steady rest to support the outboard end of the workpiece.
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    But you can't grip it close enough in the lathe chuck to minimize the part which extends, so you will have to use the fixed steady to support it just back of the 1" to be turned down.
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    I would suggest avoiding the 1/4-20, if the balls are going to be slammed around by an engrossed gamer. Any of the others should be fine, and the choice probably should be based on the thread which is easiest to cut in *your* lathe.
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    O.K. Loctite can be unscrewed -- if you heat it up with a torch first.
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    You are obviously not familiar with a roll pin. Picture a length of flat spring steel stock which has been rolled into a two-turn roll. The ends are tapered a bit to make them easy to start, and they are driven into the mating holes, with the spring expanding to grip both the parts. They can be driven out as long as the hole goes all the way through. They are available for relatively little money for large quantities. With blind holes, people have managed to use a tap to thread the ID and give a grip with a screw to pull them out.
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    Of course.
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    O.K. It could require somewhat over that 6" diagonal, if the groove has to be around a point other than the center, because it *must* rotate around the center of the groove to be.
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    O.K. I haven't worked the 5052, and it is too late to look up its characteristics, but as long as it isn't a dead soft aluminum (pure aluminum) it will probably do.
    It should be a *lot* easier to machine than the Stainless steel.
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    Given the size of the workpiece, I don't expect too much flex from 1/4" thick aluminum, let alone SS. :-)
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    O.K.
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    O.K. You can replace it with other materials if it shows as problematic.
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    O.K.
http://www.ares-server.com/Ares/Ares.asp?MerchantID=RET01229&Action Êtalog&Type=Product&IDƒ146
    What you are looking at are designed to hold flat workpieces and feed the tap in truly square to the surface. Your rod, with a hole in the end, would be difficult to mount truly vertically so the tap is guided in square.
    Let me try an ASCII drawing of the kind of tap wrench that I'm talking about. You'll need to set your screen to a fixed pitch font like Courier to keep the drawing from being distorted. __________ ___________________/ ______ \_____________________ (___________________ |__<>__| _____________________) \__________/
The diamond shape in the center adjusts to wider or narrower by turning one of the handles, which screws into the center part. This closes on the square on the end of the tap's shank, gripping it and allowing the wrench to turn the tap.
    It takes a steady hand to work with small taps with one like this. I've used them down to 0-80 taps with small versions of the wrench and with reasonable care. But your taps are large enough so you should have no real problems.
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    Did you phone them?
    Did you register with them? (They give you a customer number to     use in subsequent orders.)
    Is it possible that they delivered one and it was stolen? They     normally send the catalogs via UPS, same as the parts which they     sell. (Though the last catalog came via USPS instead, IIRC.)
    Or -- do you have a lazy mailman? One who won't deliver     anything which does not fit in your mailbox?
    Or -- it might just be that they're out of that catalog, and the     new one is just about to be printed and shipped.
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    Yep>
    Nope -- though they do on ones like my Cameron Micro Precision sensitive drill press. It is a maximum chuck capacity of 1/8" with the Albrecht chuck, though a small Jacobs 3/16" chuck can be fitted to the drill press. It is precise enough so it handles #80 drill bits (Hard to see, even in the drill index) with no problems.
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    Hmm ... Do they need to be a full 180 degrees of rounding, or just a gentle curve. The latter can be turned in the lathe. The former will take either a rotary table, or a larger mill with a corner rounding end mill.
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    I've never seen such a combination. It is something which you will have to make up out of parts which you can find and combine together. A lot of machining is making special combinations of existing tools. So -- you are highly unlikely to find such a visual. This is one of those "figure it out for yourself" tasks.
    Enjoy,         DoN.

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Yes, but they wouldn't give it that solid, heavy, durable, quality look and feel that a stainless steel ball-top would. :-)
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That would be a pain. And since this sleeve will be wedged against a (3" diameter)Delrin plate I don't think that'll work.
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It would seem to be more reliable(though not easier or cheaper) than using Delrin rods. So I'll look that up. (Tapping is going to be a subject unto itself that I'll have to study).
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The groove(which would have a 3" O.D.) would actually have to be made in the 4" square piece.
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Well, if I go with Aluminum, most of it would be turned/milled down to 1/16" thick. Only a ring(with an O.D. of 2-5/8") would be left. (And a 3/8" Delrin ring(with "cups" drilled into it for the bearings) would fit around this.
In fact the above may just be the best idea.
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I clicked "Fixed Font" on this Google page and it was no better than proportionate. But when I clicked print to bring up the printer friendly page your ASCII drawing came out perfect.
I was looking at those tap wrenches on the Grizzly catalog, so I'll have to investigate further what I'll need to drill that 1/8" diameter hole through rod and sleeve.
BTW. I suspect that the 11/16" long sleeve(tube) would be easier to buy than to attempt to drill a rod that length end to end.
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I'll try again.
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I believe I'v seen simular drill presses go for $400+ on eBay. Anyway, I can only hope that one of the $50 bench tops will allow enough accuracy for my needs. I suppose I'll need it to be pretty accurate if I go with the roll pin.
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Technically, I can leave this piece pointed at all four ends, but I just wanted to clean things up. I'm flexible, so I'll see what can be done.
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Yes. That is why I joned a Yahoo Group "mlathemods - Mini Lathe Modifications". Perhaps there will be some ideas there.
BTW. I have a line on an Enco lathe that is supposed to have a lot of tooling for $550. The seller says he thinks is a 9" by 16", but I don't know if that even exists. I've only been able to find references to a 9 X 20(#308-0338).
Thanks.
Darren Harris Staten Island, New York.

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    The Bakelite ball is pretty solid, so it may work well.
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    O.K.
    It may well be cheaper than using Delrin rods. After all, these are mass produced to standard diameters and lengths. Delrin tends to be rather expensive (though something like 1/8" diameter rods would not be that expensive, and you would simply have to turn them to the desired final diameter and cut them to length.
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    Indeed so.
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    But -- the groove could be off towards one corner, so it is just barely grazing two sides, and that would result in the other sides extending 1" beyond what would be the case with a centered plate. And that would be 1.414" beyond at the corner. So -- what would have been a 5.65" diameter if centered would be closer to an 8.48" effective diameter. This is why I specified the center point of the groove being important.
    Granted, I suspect that the groove *will* be centered, but I want to point out the problems you can have if you make that assumption blindly.
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    O.K.
    Ouch! -- You are using *Google* for this? I'm glad that you found a way to get it to display properly. And I had to re-adjust the tap wrench to correct for whatever Google did to it when you quoted it in your followup.
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    For that -- I would suggest that you look for a bench block (Starrett makes two sizes, and you would want the smaller of the two.) Check out eBay auctions 7587959068 and 7587168821 to see what they look like. The first auction has only eight minutes left as I type, so you are unlikely to get it.
    But -- the V-groove supports the shaft (and the sleeve), and there is a small hole at the bottom of the V-groove to clear the drill (or to clear a pin when it is being driven out).
    The second one is being sold from the UK, and who knows who really made it. It looks nice, at least.
    The last one is also a Starrett, but is the larger one, and I think that it would be less satisfactory.
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    Perhaps -- if you can find the right size. Or, you might be able to buy it as a long sleeving, and part it off to length.
    [ ... MSC catalog ... ]
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    You might mention that you tried before, and never got a catalog.
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    Mine was $150.00 new -- but that was back around 1972 or so, and prices have increased since then. :-)
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    The roll pin expands to fit the hole, within reason. But without special fixturing (other than the V on the top of a bench block), I would suggest that you drill through both the sleeve and the rod at the same time. The hole may wind up a bit off center, but it will be the same for both parts, so the roll pin should fit through it easily enough.
    Now -- if you were using a dowel pin, you would need a very precise hole diameter. Drill it a bit undersized, and then use a hand reamer to take it to the proper size.
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    O.K. So just chuck it in the 4-jaw, as well centered as you can manage, and then turn the OD to produce the curved ends, which may well be enough.
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    O.K. Good luck there. There will be things which you will have to design for yourself.
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    Since I don't have an Enco catalog on hand, I've no idea whether they currently have (or ever had) a 9x16". The shorter it is, the lighter, as the bed adds significant weight.
    Good Luck,         DoN.

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I do have a lot of Delrin that I could probably make as many pins as I'd need.(Though turning it down to 1/8" of an inch may be asking a lot of the lathe). :-)
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It'll be centered so that it'll be four inches from each of the four sides.
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What if I used a sharp punch of some sort to start, followed by a center drill in the lathe, and then drill after that? since the 1/8" hole is only 1/8" from the bottom I'd probably have to balance things by using a tube with a 7/16" I.D. to fit over the rod/sleeve, effectively lengthen it so it would slip out of the chuck.
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Reamers happen to be on my shopping list. :-)
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I already have a couple of tool post mods in mind. :-)
Thanks.
Darren Harris Staten Island, New York.

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    Hmm ... how big is the Delrin to start? Anyway, if you are turning a length down to 1/8", and the length is something like 9/16" or so, it *will* bend as you try to turn it. The way to accomplish the task is:
1)    Start with a very sharp HSS tool -- ground to the angles     which are right for turning Delrin. (Note that carbide inserts     are usually a bit too dull to do this job well, though the tiny     uncoated inserts for my Compact-5/CNC tend to be quite sharp     enough. They are hard to find, and are usually quite expensive.
2)    Turn only the end-most 1/8" down to 1/8" diameter.
3)    Then turn the next 1/8",
4)    Repeat until you have enough length to part it off to your final     length.
    And -- don't have any more of the Delrin sticking out of the chuck than you plan to turn for that one part.
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    Hmm ... how do you plan to use the lathe for this? I thought that the hole was from one side to the other, not into the center of the end.
    If the holes must *all* be the same distance from the end, you will want a V-block clamped to the drill press table, with a stop to keep you from sliding the workpiece in too far.
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    O.K.
    Good Luck,         DoN.

DoN. Nichols wrote:
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I have Delrin of Different shapes, but I'd use the scraps which are basically about 1-1/2" x 2.00" X 12". I'd take it to a band saw first to make it manageable for the lathe to turn down.
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Thanks. from what I've read, I should treat Delrin like Stainless steel as far as the sharp tool and cutting speeds.
I also have several 4" diameter Delrin cylinders that are about a foot long, I'll be slicing them into 3/16" or 1/4" thick disks that I'll need to do six plunging operations involving making different sized holes/slots in each of six equal "pie" slices.
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I think my wording int hat last paragraph was bad, because a chuck couldn't be used.
First I wanted to be clear that the purpose of the S.S. sleeve situated around the turned down portion of the S.S. rod would be to keep three 1/16" plates(Delrin/stainless/Delrin) from sliding off.
Now. yes, the 11/16" long(7/16" diameter) sleeve will have the turned down end of the rod already inserted into it so I can drill the 1/8" diameter hole all the way through *both* at the same time. That 1/8" diameter hole will be located only 1/8" from the end, so gripping it so it could be drilled would pose a problem.
My idea is to make a "holder" out of a 5-1/2" long, (perhaps 1" diameter) steel rod. I'd mill a 7/16" wide slot(1/2" deep)down about half of it's length, so I can place the work(S.S. rod/sleeve)inside it. The un-slotted end of this "holder" would be bolted to a face plate, and the threaded end of the work(opposite the sleeve) would be screwed into a 1" square block which would also be bolted to the face plate. This would keep the work(S.S.rod/sleeve) from turning in the "holder".
After it is secure to the faceplate, drilling all the way through it would entail a tool steel punch, followed by a center drill, followed by a drill bit to get the 1/8" diameter hole(all the way through).
Now of course I'd have to slot and drill through the "holder" first. :-)
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Ok. If a $50 drill press would be easier then I will get one.(Hopefully better than my last one).
P.S: I'd like to point out that I discovered that the 5/8" thru-hole in my lathe was not a reference to the spindle bore. The spindle bore is .787".
This is the part that I misinterpreted: "3-jaw self-centering chuck (bolts to spindle: 2-3/4 inch capacity, approx. 5/8 inch dia. thru-hole)."
Thanks a lot.
Darren Harris Staten Island, New York.

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    You are going to be making a lot more chips than parts, starting from that size. A serious bit of waste in my book. And, you *will* need the 4-jaw independent chuck to hold those rectangular pieces.
    Hmm ... look at the MSC web site:
    http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO54707&PMT4NOG49765
which shows 1/8" Delrin (acetal) rod, 1 foot long, for 98 cents each. Your choice of black, or natural (fairly white). Hmm ... that looks like Teflon (PTFE), not Delrin (acetyl).
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    O.K.
    O.K.
    Hmm ... I would not bother with the center punch given that setup, as long as the holder (fixture) which you describe below remains fixed in position between workpieces.
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    As I say -- the punch probably is not necessary. Just start the hole with the center drill. (You can get them down to 1/8" diameter, which would make a great start for the hole.
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    Your setup on the faceplate would work. But you would need to add a counterweight on the faceplate to allow it to balance properly so you could run at reasonable speeds for a 1/8" drill bit.
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    O.K. That is better.
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    So -- holding workpieces with that chuck will still limit you to the 5/8" diameter which will fit through that chuck. Other chucks may allow larger diameters.
    Enjoy,         DoN.

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Yes. I'm thinking a 5" chuck with a spindle bore that is at least .787" would be preferrable.
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At 98 cents, that's obviously the better way to go. I'll save the Delrin scrap I have for something else.
I'm assuming that Delrin would be the best choice as far as plastics, but my first choice is your idea to use the roll pins. It would seem that they would withstand shearing forces better.
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BTW. If there is a way to do this using my lathe, the drill would have to be at the headstock end, and I'd need something like a six-sided collet block in something not only large enough to hold a 4" disk, but also position it at varyng heights above the bed.
So obvious a drill press and a rotary table would be the easiest and cheapest way to go for this.(I'd have to "overlap" drill holes to make slots).
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Yes. I'd ahve to make a dedicated face palte and holder just for this.
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Yes. I believe that would be the #1 center drill.
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Hmm... My original thought was to drill out the solid end of the holder(a little at a time) which at the start would be slightly heavier than the side holding the work and Aluminum block. until the weight on both sides of the center axis(drill point) was equal. This would be determined by balancing the center axis on a straight edge. But if this is a bad idea I'll entertain your suggestion.
Thanks. Darren Harris Staten Island, New York.

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    That sounds reasonable.
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    Good!
    Well ... "best choice" varies with what you need it to do. I might consider a fiberglass/epoxy to be stronger, or even a graphite epoxy composition. But it is not yet clear how much strength you really *need*.
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    There are 3-jaw chucks, and 4-jaw chucks, available with 5C collet style shanks -- designed for when a larger lathe needs to handle smaller workpieces. Combine this with a collet block and a lathe based milling attachment and you could probably make a go of this. The question is how deep and how long the slots will be. If they are all the way through, and continue out to near the edge of the disc, you will have problems as the workpiece will collapse when enough material has been removed.
    For that -- perhaps replace the chuck with a faceplate, and find positions in the workpiece which can accept bolts to secure it to the faceplate (perhaps with some sacrificial material under the workpiece, so you don't mill into the faceplate itself.
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    Smooth slots would be difficult to make this way. Drill bits tend to bend when you're trying to partially overlap with another hole. If you space the holes such that they are almost a full drill diameter apart, and then make a second pass, drilling through the center of the web between them, you will wind up with a scalloped structure which you can then smooth out with a file.
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    O.K. Start collecting faceplates to fit your lathe. :-)
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    That sounds right.
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    Simply mount a lighter counterweight to one of the faceplate slots, secure it with a bolt through the slot, and adjust it outwards until it counterbalances the workpiece and the fixture. A lot easier than repeated machining until you get close to the right size.
    Good luck,         DoN.

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That is why it is best to go with the strongest material I can find. A material that will best withstand the kind of force generated(when a 3/32" wide area attermpts to shear off a 3/32", 1/8" diameter pin).
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I don't know of a better plastic for this. Basically any of six holes/slots of various shapes(drilled all the way through the Delrin) would fit within a 1-1/4" area and there will be a minimum space of 3/16"-1/4" between any of them. This is one reason why I was thinking a drill press might be the best way to go.(Rpms would be a big guess at this point).
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That's the plan. :-)
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Yes, perhaps "overlap" was a bad word to use. You described my intentions. I've read about how drills catch the material on one side when attempting to drill partly over another hole. The method you described evens out those forces on opposite sides of the drill bit.
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Yes, but how would I determine when it was balanced?
BTW. After some more thought, perhaps a holder made completely out of Aluminum instead would be better. The holder/work combination would be lighter as a result, but the heavier side would now be the half that encompasses the work.
Thanks.
Darren Harris Staten Island, New York.

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    Hmm ... that depends on whether you *want* it to shear to protect the rest of the system at some point, or whether you want it to hold on as long as possible.
    If the latter, I would suggest either a hardened dowel pin, or a solid carbide pin.
    For the former, the material is selected based on the maximum force which you want it to transmit before it fails gracefully. examples of this are things like the shear pin in the connection of a propeller to an outboard motor, so the propeller survives when it hits a rock or a log. Or a pin connecting the quick-change gearbox on a lathe to the leadscrew, so if the carriage gets wedged, the pin will shear, instead of losing teeth from the gearing.
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    Remember -- the slot will be scalloped -- at least until you can file it smooth -- assuming that you have a place to run the file to do that.
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    Switch on the lathe spindle at a low speed, without planning to make a cut. If the lathe doesn't try to walk off the table, keep increasing the spindle speed to see where it does try to walk off the table. The higher you can get the speed without things galloping around, the better. If it does start bouncing, stop it, move the counterweight either a bit more distant from the center or closer. Try again. If the problem occurs at a lower speed, you moved it the wrong way.
    Since you're going to be drilling steel with only a 1/8" diameter drill bit, you will probably want something close to the maximum speed the lathe is capable of. (Check the SFM recommendations for the drill bit material in the material you are drilling and compare it to the results of calculation to determine the desired spindle speed.
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    Play with it until you get the right results.
    Enjoy,         DoN.

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Then having the pin stay in place would again be an issue.(And corrosion resistance is still important).
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I have a Dremel. :-)
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Do you know if I can I buy these counter weights or do I have to make one myself?
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SFM recommendations?
Thanks.
Darren Harris Staten Island, New York.

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    Do you *really* need that much strength? The roll pin should be plenty. I consider the dowel pin or the solid carbide pin to be seriously extreme conditions.
    Note that with a dowel pin, you would drill the hole through the shaft slightly undersized, and use an undersized reamer to make it a just *barely* undersized hole.
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    Yes -- but I don't find a hand operated Dremel to produce that smooth a slot.
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    A counterweight consists of:
1)    A chunk of scrap metal of about the right weight, drilled and     tapped for a bolt.
2)    A bolt which fits through a slot in the faceplate.
3)    Probably, a flat washer to spread out the contact of the bolt     head to the underside of the faceplate.
    Of *course* you make it yourself. Until you are set up, you don't know how much weight you will need. If it is not too much, put a bolt through from the back, with washers on both sides of the faceplate, and then start adding nuts to the bolt until you have the right weight.
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    Material specification, first?
1)    What material you are drilling? (IIRC, it was a stainless     steel, but don't expect me to remember which stainless steel.
2)    Drill bit material? You've got the choices of Chinese or     Indian pseudo-HSS, a real US (or European) made HSS, a high     cobalt steel (and which percentage), or a solid carbide drill     for starters. Also, there are various coatings TiN, TiAlN, or     various others which affect the friction, and thus the proper     speed.
    Also -- some of the better ones will have polished parabolic     flutes, which will reduce the friction even more, with or     without coatings.
    Drill bit grind. There are various angles available for normal     tips, plus there are split tips, which replace the chisel point     (which sort of rubs material out of the center area) with     secondary cutting edges, which will allow you to drill with a lot     less force, and will produce less heat.
    I don't know which you will opt to buy.
    And which lubricant/coolant will you be using? That affects     your choices as well -- and may interact with some of the other     choices. (Speaking of lubricant/coolant -- I would suggest that     you hang something behind your lathe (between it and the wall)     to avoid a line of coolant/lubricant spray forming on the wall.     (After all, someday you will be moving out of that apartment,     and not having to pay to re-plaster the wall could be a     significant savings.
    Personally, I would probably go with a cobalt steel bit, with     split point, parabolic polished flutes in screw machine length,     and would spend some time looking for the best coating to use --     *if* I were going to be making thousands of these.
    If I were going to make only a few, I would pick a good drill     bit from the set which I have -- or maybe a brand new one for     drilling SS -- and just select a speed which would be safe for     the bit. (But I don't buy Chinese drill bit sets, and I *do*     have a cobalt steel set of number-sized bits in screw-machine     length and split points as one of my things ready to hand.
    If it comes down to chosing the *right* SFM, I would pick up my     copy of _Machinery's Handbook_ (a recent edition), and look up     what the proper SFM would be for the combination. And I would     then probably use something a bit slower, as these are for     massive production, and are a speed selected to make the optimum     tradeoff between the time the job takes and the life of the     drill bit. And the time taken to change the bit counts for more     than the cost of the bit in this equation. You won't have     production capable machinery, so don't push it.
    The chart on page 1030 of the 24th edition of _Machinery's     Handbook_, for 303 SS (among some others) suggests for HSS that     you use a SFM of 20 (Opt) or 40 (Avg), with a feed of     0.015" per revolution (Opt) or 0.007"/rev (Avg)
    The other column for drilling assumes indexable insert drills,     which make no sense at the size were you are working.
    I'm not sure how you are going to manage a known feed rate while     drilling in the lathe, unless you mount a drill chuck to the     toolpost and set the feed gearing to accomplish that.
    Anyway, for a 1/8" drill bit, and the slower SFM listed for HSS,     I see something like 611 RPM, which you would have difficulty     hitting exactly, anyway.
    There seems to be no point to checking out the right speeds for     indexable carbide insert drills, as they don't make any that     small.
    By comparison, the speeds for 12L14 (and other free-machining     steels) are 365 (Opt) and 740 (Avg). The slower of those two     calculates out to about 11,153 RPM. And the 12L14 will not work     harden if you pause in the drilling for a moment, while the SS     is very likely to.
    So -- make a copy of _Machinery's Handbook_ one of your     purchases. The answers to *many* of your questions can be found     there, and I will henceforth assume that you have one for such     questions.
    Enjoy,         DoN.

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There really is no way todetermine howmuch force thepin would be subjected to, which is why I said I want to go with the stongest corrosion resistant material that would stay in the hole.(If it fails, I'll just have to try something else).
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I've only seen bits and reamers in 1/8" size increments.
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I see deburring bits and simular in the Dremel catalog. The various Dremel tools have different bits for different operations on wood, plastic, and metal(including stainless). I'll see if anyone at the Dremel forum has any ideas.
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303 stainless steel.
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As a firm believer(victim) of Murphy's law I tend to lean towards getting the best within reason, even it if is over-kill. Hence, my penchant for "over-manufacturing". :-)
As for the drill bit. The most use I can get out of it for what I paid is a priority(using 303 stainless steel and a common standard lubricant). So the idea is to get a general idea of what the best bits are.
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Ok. Since "time" is a complete non-factor for me, would a 20% drop in the rated rpm and/or feed rate suffice?
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?!? Mounting a drill chuck to the tool post is something I've not read about before.(Back to the drawing board).
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I expect that when it arrives, it'll clear up some things.(I hope that the 25th edition is late enough). Should I also look for the guide that is commonly advertised for use with these?
BTW. UPS left a nameless notice at my address for three consecutive days. Now since four of the eight family's in this partcular complex live at the same address, if there is no name then no one would know who is supposed to be getting a package. Anyway, I get a card in the mail UPS stating that they made three attempts to deliver a package from MSC... I could go on and on about my past problems with UPS(and the neighborhood driver in particular), but... (Sigh).
Thanks a lot.
Darren Harris Staten Island, New York.

snipped-for-privacy@mail.con.com wrote: [big snip]
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What also works is to tell the sender (MSC) to mark the package to be held at the local UPS depot for customer pickup. It also works to call UPS upon a failed delivery attempt and ask that the package be held for pickup. The phone number should be on the nameless note. I've done this with computers, which are too expensive to risk just leaving them on the front stoop.
Joe Gwinn

Joseph Gwinn wrote:
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Yes I know. The package is obviously a catalog.
Having to pick up anything via UPS is totally inconvenient for me. I'd have to make a 2 hour round trip, not including the possibility of a long wait on line there.
I'm surprised that the driver made "three attempts"(even though he probably comes down my street every weekday day anyway). He doesn't always ring the bell. And tends to put the wrong time on the notice.
One of my biggest problems with UPS is that they purposely don't inform unaware senders that UPS doesn't deliver to Post Office boxes.(And if you dela via eBay, you occasionally come across people who don't know). UPS lets the package go through the system(including the "3 delivery attempts"). They return the package to the sender and make them pay again if they want it delivered.
Darren Harris Staten Island, New York

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a)    It is a joystick, right? And the pin (roll or dowel) will be in     shear only if someone is pulling up on the ball, right? Assume     the heaviest guy is say 300 pounds (as anyone heavier would     probably not be able to lift his own weight with even a     two-handed pull-up, let alone with a single-handed one.
    Personally, I think that he could not shear the pin without     first breaking something else, such as the mounting of the whole     assembly.
b)    If the whole game weighs 300 pounds, you probably don't *want*     someone to be able to lift it by the joystick ball, so it would     be better to use a pin which *would* shear first to protect the     rest of the machine.
c)    The roll pin will be a spring grade steel, *not* a stainless,     so it would be vulnerable to corrosion anyway. (So would the     dowel pin, for that matter.) *Except* that it is not out where     it can be handled, and unless someone is going to be pouring     pints of sweat down the shaft, I see no problem.
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    If you go to the industrial places (such as MSC, if you ever     succeed in getting the catalog), you will find that you can get     the sizes in just barely over the nominal size (probably     something like 0.0002" or so) to allow a slide fit on the dowel     pin, and also in just barely under the nominal size (by about     the same amount), so the dowel pin would be a press or drive     fit.
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    The main problem is having a steady enough hand to control it as you use it to open up the jagged slots.
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    O.K. I think that I posted that as an example. When you get your _Machinery's Handbook_, you can look it all up there.
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    O.K. I would suggest going for cobalt steel bits with split points, and unless you need the extra length, go for screw machine length bits. They are shorter, and flex less as a result.
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    You can contact the drill bit manufacturers and talk to someone there to give you the best that *they* make, at least.
    Buy the drill bits in envelopes of ten (I think that is the standard package size for 1/8" drill bits and similar.
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    Sure. Maybe even a 50% drop.
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    You can get quick-change tool holders -- at least for the AXA size and larger) which have a Morse taper. Get one which matches the taper in the tailstock -- or adaptor sleeves to reduce if necessary -- and you can mount the tailstock drill chuck in the toolpost, parallel to the axis of the lathe spindle.
    The major problem with it is that you have to be careful to both adjust the height of the tool holder (only once), and you have to adjust the position of the cross slide to be precisely in the middle of the spindle's axis -- *every* time you go back to that after doing something else with the lathe.
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    That is the latest that I have. I don't know what the later editions may cover that the 25th does not. I would also suggest that you look for a much older version, such as around the 15th or 16th, to pick up some of the advice which has been dropped in the more recent ones, in part thanks to the move from manual work to CNC work.
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    I have one for the 23rd edition, along with the main handbook, and I've never used it. *You* may find it useful -- I don't know. My copy came for free with the handbook -- both were a gift from someone who was shutting down a machine shop.
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    This suggests that you need to find a *service* to receive things for you, because MSC uses UPS for all their shipments which are not too heavy. I suspect that it was your catalog.
    Good Luck,         DoN.